The present invention relates to a method of acoustically counting particles of seed, fertilizer, and other materials employed in agriculture, in which the particles to be counted are conveyed against an impact plate in such a way as to start it oscillating, generating electric signals that are processed to determine the number of particles. The invention also relates to a device for carrying out a method of this type and having an impact plate that is struck by the particles to be counted, a sound transducer that converts the oscillations of the impact plate into electric signals, and a processor to process the signals.
A device of this type that operates in accordance with a method of the same generic type is described in German OS No. 2 901 767. The particles encounter a microphone that detects the noise of impact when a number of particles strike its diaphragm. Electric signals resulting from the impact noise are supplied to an amplifier that generates an output signal when the noise is loud enough. This known device makes it possible to grossly indicate larger amounts of particles. It is accordingly especially practical when the precise number of individual particles is not especially important but only the fact that particles are present at all. The method and device are not appropriate for counting individual particles, for example, seed that is to be sown.